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Circular  No.  33,  Second  Series.    (Supplementary  to Clrculari  18 and 27.) 

United  States  Department  of  Agriculture, 

DIVISION  OF  ENTOMOLOGY. 


REMEDIAL  WORK  AGAINST  THE  MEXICAN  COTTON-BOLL  WEETIL. 

In  the  course  of  the  investigations  of  the  boll- weevil  problem  in 
southern  Texas  in  the  spring  of  189G  by  my  first  assistant,  Mr. 
C.  L.  Marlatt,  it  was  early  discovered  that  the  overwintered  weevils 
were  not  only  collecting  on  the  volunteer  cotton  but  were  feeding  to 
a  noticeable  extent  on  the  expanding  leaves  and  soft  green  stems  of 
the  new  shoots.  The  possibility  of  destroying  the  beetles  by  wetting 
this  new  growth  by  an  arsenical  poison  at  once  suggested  itself,  and 
experiments  which  were  promptly  instituted  with  confined  beetles  on 
small  plants  demonstrated  conclusively  that  not  only  do  the  beetles 
feed  on  the  leaves  and  tender  shoots  voraciously,  but  that  by  poisoning 
such  shoots  the  beetles  subjected  to  experiments  could  all  be  killed 
in  the  course  of  8  to  12  hours. 

A  more  general  experiment  to  test  the  value  of  poisoning  was 
instituted  in  a  field  containing  much  volunteer  cotton  which  had 
already  (April  26)  made  considerable  growth,  forming  rather  dense 
bushes.  This  experiment  was  carried  out  on  the  farm  of  Judge 
Borden,  of  Sharpsburg,  the  plants  being  sprayed  from  an  ordinary 
wagon  cart.  Great  difficulty  was  experienced  in  wetting  more  than 
the  outer  leaves,  which  were  now  of  large  size  and  protected  much 
of  the  inner  growth,  especially  the  squares.  The  outcome  of  this 
work  demonstrated  that  while  the  poisoning  of  the  cotton  plant  was 
thoroughly  feasible  and  practicable  when  done  at  the  right  season 
and  would  result  in  the  killing  of  the  overwintered  weevils,  if  delayed 
too  long  it  was  very  unsatisfactory  and  promised  very  little  of  value. 
In  other  words,  it  is  much  more  difficult  to  poison  plants  successfully 
as  a  means  of  destroying  the  weevil  than  to  poison  them  for  the 
cotton-leaf  worm,  which  feeds  very  often  if  not  generally  on  the  outer 
leaves  and  can  be  reached  by  powder  dusted  over  the  plant  in  the 
most  careless  and  general  way.  The  weevil,  on  the  other  hand,  feed- 
ing as  it  does  on  the  tender  growing  tips  and  on  the  flower  buds, 
which  are  very  often  concealed  and  covered  up  by  the  larger  leaves 
of  older  growth,  requires  for  its  destruction  very  careful  and  thorough 
spraying,  such  as  would  be  impossible  after  either  volunteer  or  planted 
cotton  has  reached  any  considerable  size. 


SB 

&33 


As  a  means,  however,  of  destroying  the  overwintered  weevils  on 
volunteer  cotton,  a  spraying  of  poison  in  April  promised  very  valu- 
able results,  and  a  recommendation  for  such  treatment  was  inserted 
in  the  last  edition  of  the  boll- weevil  circular  (Circular  No.  18,  second 
series),  as  follows: 

The  beetles  which  have  survived  the  winter  collect  in  the  early  spring  on  the 
first  sprouts  which  appear  on  old  cotton  and  eat  the  partially  expanded  leaves 
and  the  tender  leaf  stems,  and  at  this  stage  can  be  poisoned  by  the  application 
of  an  arsenical  to  this  new  growth.  To  do  this  it  will  be  necessary  to  thoroughly 
spray  the  growing  tips,  and  this  should  be  done  when  volunteer  cotton  is  very 
small,  preferably  mere  sprouts  or  bunches  of  leaves  an  inch  or  two  in  length ; 
later  on  the  growing  parts  can  not  be  easily  reached.  With  an  ordinary  knap- 
sack pump  a  field  may  be  gone  over  rapidly  and  the  volunteer  cotton  thoroughly 
treated,  the  nozzle  being  directed  at  each  growing  tip.  The  first  application  should 
be  made  as  soon  as  the  volunteer  plants  sprout,  and  perhaps  repeated  two  or  three 
times  within  as  many  weeks.  As  ordinarily  cultivated,  the  number  of  volun- 
teers is  small  and  the  time  required  for  the  thorough  spraying  of  such  plants  will 
not  be  great.  A  strong  solution  should  be  applied,  viz,  1  pound  of  the  poison  to 
50  gallons  of  water,  because  no  harm  will  be  done  if  the  volunteer  plants  are 
ultimately  killed  by  the  poison. 

The  use  of  poisons,  either  London  purple  or  Paris  green,  as  described 
in  the  paragraph  quoted,  is  thoroughly  practicable  and  undoubtedly 
will  be  of  value.  The  careful  study,  however,  of  the  weevil  dam- 
age in  Texas  conducted  by  the  Division  during  the  last  three  or 
four  years  has  demonstrated  that  the  prevention  of  weevil  damage  is 
more  a  question  of  the  adoption  of  a  proper  system  of  cultivation 
than  of  remedial  or  preventive  schemes,  such  as  the  use  of  poisons. 
In  other  words,  it  is  admitted  by  intelligent  planters  everywhere  that 
the  presence  of  the  weevil  is  made  possible  by  a  system  of  culture 
which  admits  of  the  existence  of  volunteer  cotton,  and  if  the  methods 
followed  are  such  as  to  prevent  such  volunteer  growth  the  weevil 
will  rarely  if  ever  be  troublesome. 

In  our  publications  on  this  insect,  therefore,  great  stress  has  been 
given  to  the  cultural  method  of  control,  which  is  undoubtedly  the  one 
thoroughly  effective  means  of  avoiding  loss  from  the  boll  weevil. 
The  details  of  this  method  are  repeated  at  the  close  of  this  circular. 

Unfortunately  a  great  deal  of  the  cotton  culture  in  Texas  is  of  the 
rather  careless  sort,  and  there  probably  always  will  be  more  or  less 
volunteer  cotton  infields  unless  very  stringent  regulations  are  passed 
and  great  care  is  taken  to  see  that  these  are  strictly  enforced.  The 
poisoning  of  volunteer  cotton  in  early  spring  remains,  therefore,  a 
procedure  of  importance  and  of  considerable  practical  utility. 

The  present  season  attention  has  again  been  directed  to  this  or  a 
very  similar  method  of  control,  in  the  course4  of  the  investigation  of 
the  weevil  conditions  in  Texas  by  Professor  Townsend,  a  field  agent 
of  the  Division.      In  the  course  of  this  work  it  was  discovered  that 


3 

tho  weevils  seemed  to  have  a  marked  fondness  for  sweets,  such  as 
molasses,  and  would  eat  the  latter  when  smeared  on  cotton  stalks  or 
young  shoots  either  with  or  without  an  admixture  of  arsenic.  A  fter 
eating  the  poisoned  sweets  the  beetles  died  within  8  to  )l\  hours. 
After  some  weeks  of  experimentation  in  the  field,  chiefly  at  Cuero, 
Tex.,  Professor  Townsend  recommends  and  indorses  very  heartily  two 
formulas,  one  for  the  treatment  of  young  planted  cotton  and  the 
other  for  the  destruction  of  the  overwintered  beetles  on  the  volunteer. 

FORMULA   FOR   VOLUNTEER   COTTON. 

The  undiluted  molasses  is  mixed  with  one-fourth  its  volume  of 
arsenic  and  applied  to  the  volunteer  stalks  in  spring  when  the  leaves 
are  beginning  to  appear.  The  molasses  must  be  kept  well  stirred  to 
prevent  the  arsenic  from  settling,  and  may  be  smeared  on  the  stalks 
of  the  volunteer  cotton  with  a  stick  or  brush.  All  untreated  plants 
must  be  killed  and  only  a  few  poisoned  plants  should  be  left  to  the 
acre.  This  applies  to  districts  where  the  foliage  of  the  cotton  is 
killed  in  winter.  In  warmer  districts,  where  the  foliage  is  not  always 
killed  in  winter,  all  but  a  few  of  the  plants  should  be  killed  and  up- 
rooted, and  the  remainder  smeared  with  the  poisoned  molasses,  all 
squares  and  bolls  having  been  removed  to  insure  the  quickest  effect. 
It  is  believed  that  the  weevils  will  be  attracted  to  these  poisoned  plants 
by  the  molasses  and  will  be  killed,  and  this  will  obviate  the  necessity 
of  treating  the  young  planted  cotton. 

FORMULA   FOR   PLANTED    COTTON. 

White  arsenic  (arsenious  acid)  If  to  2  ounces  boiled  in  a  gallon  of 
water  until  thoroughly  dissolved ;  two  or  three  gallons  of  the  cheapest 
grade  of  molasses,  and  one  barrel  (40  gallons)  of  water.  Stir  the 
molasses  into  the  water,  then  add  the  dissolved  arsenic  and  mix  the 
whole  thoroughly.  Apply  to  the  plant  with  a  force  pump  and  spray 
nozzle  as  in  spraying  for  the  cotton-leaf  worm. 

This  mixture  is  designed  for  use  particularly  on  young  cotton 
plants,  and  may  also  be  used  for  the  poisoning  of  volunteer  cotton 
with  a  knapsack  sprayer  or  larger  apparatus,  as  described  in  the 
quotation  from  Circular  18.  The  only  advantage  of  the  sweetened 
or  sirupy  wash  over  Paris  green,  London  purple,  or  arsenite  of  cop- 
per, as  ordinarily  used,  is  in  its  being  supposed  to  attract  the  weevil ; 
so  that,  even  although  the  entire  plant  might  not  be  wetted  with  the 
mixture,  the  weevil  would  be  attracted  by  the  sweetened  bait  to  the 
parts  struck  by  the  liquid. 


It  should  be  remembered  that  the  white  arsenic  recommended  is 
very  caustic  and  is  very  much  more  apt  to  burn  or  scald  plants  than 
are  the  other  arsenicals  just  mentioned,  and  it  is  quite  probable  that 
either  London  purple  or  arsenite  of  copper,  which  are  of  about  the 
same  cost  as  white  arsenic,  will  be  preferable  to  the  latter. 

The  cheap  grade  of  molasses  referred  to  can  be  laid  down  in  Texas 
at  a  rate  of  10  cents  per  gallon.  White  arsenic  costs  about  10  cents 
a  pound  retail,  but  wholesale  can  be  obtained  for  much  less.  London 
purple  and  Paris  green  also  cost  about  10  cents  a  pound  retail.  A 
barrel  of  the  mixture  at  the  prices  quoted  will  cost  about  25  cents, 
and  should  spray  an  acre  or  more  of  young  planted  cotton.  The 
much  heavier  mixture  for  volunteer  cotton  is  used  in  very  limited 
quantities  and  a  small  amount  will  cover  a  large  area.  The  direc- 
tions and  cautions  given  at  the  outset  for  spraying  for  the  boll  weevil 
are  equally  applicable  to  the  molasses  and  arsenic  wash  described. 
For  field  work,  however,  a  large  machine  is  necessary,  such  as  the 
mounted  horse  spray  machines  commonly  used  for  treatment  of 
potato  farms. 

It  should  be  remembered  that  this  treatment  rests  merely  on  some 
preliminary  experiments  made  with  confined  weevils  on  poisoned 
plants,  and  its  success  on  a  large  scale  remains  to  be  demonstrated. 
Its  greatest  value  will  come,  undoubtedly,  in  the  treatment  of  vol- 
unteer plants  and  young  planted  cotton,  and  its  success  with  the  lat- 
ter will,  undoubtedly,  diminish  as  soon  as  the  plants  have  formed  a 
head  or  become  at  all  bushy.  It  is  given  publicity  by  means  of  this 
circular,  to  get  planters  to  test  it  fully  in  field  trials,  which  alone  will 
demonstrate  its  value  or  worthlessness. 

THE  CULTURAL  METHOD   OF   CONTROLLING  THE  BOLL  WEEVIL. 

It  should  be  remembered  that  the  poisoning  of  the  volunteer  and 
also  of  the  young  planted  cotton  is  suggested  merely  as  a  means  of 
correcting  a  condition  which  has  resulted  from  imperfect  cultivation, 
and  that  the  great  value  of  the  cultural  method  of  control  should 
not  be  lost  sight  of. 

The  description  of  this  method  given  in  our  last  circular  on  the 
boll  weevil  is  as  follows : 

The  careful  investigation  of  this  weevil  during  the  past  two  or  three  years  by 
the  Division  of  Entomology  has  fully  demonstrated  the  supreme  importance  of 
the  cultural  method  of  control,  to  which  fact  we  gave  special  prominence  in  our 
first  circular  on  this  insect.  There  can  be  no  question  now  that  in  the  proper 
system  of  growing  cotton  a  practically  complete  remedy  for  the  weevil  exists. 
In  the  first  place,  it  has  been  established  beyond  question  that  the  conditions  of 
cultivation  which  make  volunteer  growth  possible  also  make  the  continuance 


of  the  weevil  inevitable.  Of  first  importance  is  the  early  removal  of  the  old 
cotton  in  the  fall,  preferably  in  November  or  earlier.  This  can  be  done  by  throw 
ing  out  the  old  plants  with  a  plow,  root  and  all,  and  afterwards  raking  them 
together  and  burning  them.  This  treatment  should  be  followed,  as  promptly  as 
may  be,  by  deep  plowing,  say  to  a  depth  of  C  or  8  inches.  This  leaves  the  field 
comparatively  clean  of  old  cotton  stalks,  facilitates  thorough  cultivation  the 
following  year,  and,  at  the  same  time,  collects  and  destroys  all  the  weevil  larvae 
and  pupae  in  the  cotton  at  the  time,  and  also  most  of  the  adults.  The  escaping 
beetles  will  be  buried  by  deep  plowing,  and  will  not  again  reach  the  surface. 
Few,  if  any,  of  them  will  succeed  in  hibernating  in  the  absence  of  the  ordinary 
rubbish  in  the  fields  in  which  they  winter.  Fields  treated  in  this  way  have  given 
a  practical  demonstration  of  the  usefulness  of  the  method. 

The  greatest  danger  from  the  weevil  is  due  to  the  presence  of  volunteer  cotton, 
which  means  early  food  for  the  weevils  in  the  spring  and  abundant  means  for 
their  overwintering,  and  the  effort  made  to  retain  volunteer  and  get  early  cot- 
ton, or  the  "first  bale,"  is  a  very  serious  menace  to  cotton  culture  within  the 
weevil  district. 

This  cultural  method,  if  generally  practiced,  will  undoubtedly  prove  a  perfect 
remedy  for  upland  cotton,  and  will  vastly  reduce  weevil  damage  in  the  lowlands, 
where  the  weevil  is  more  apt  to  winter,  perhaps  in  adjoining  woods  or  roadside 
vegetation.  The  early  removal  of  cotton  by  the  means  suggested  is  especially 
advised  whenever  the  presence  of  the  weevil  shows  that  the  picking  of  a  top 
crop  is  problematical.  In  such  instances  it  would  be  well  to  uproot  and  destroy 
cotton  stalks  in  September  or  October,  as  would  have  been  thoroughly  feasible 
for  much  of  the  upland  cotton  in  1896.  If  this  cultural  method  can  be  enforced, 
either  by  State  legislation  or  by  the  cooperation  and  insistence  on  the  part  of 
landowners  that  their  renters  shall  carry  out  the  system  outlined,  the  weevil 
difficulty  can  undoubtedly  in  very  large  measure  be  overcome. 

In  connection  with  the  system  of  fall  treatment  of  the  cotton,  constant  and 
thorough  cultivation  of  the  growing  crop  as  late  as  possible  is  of  considerable 
value,  and  is  also  what  should  be  done  to  insure  a  good  yield.  With  a  crossbar 
to  brush  the  plants  many  of  the  blossoms  and  squares  containing  weevils  will  be 
jarred  to  the  ground  and  buried,  together  with  those  already  on  the  ground,  in 
moist  soil,  and  a  large  percentage  of  the  material  will  rot  before  the  contained 
insects  have  developed. 

Somewhat  in  line  with  the  last  paragraph  is  the  collection  and  de- 
struction of  the  infested  bolls  and  weevils  from  the  plants  themselves. 
A  complex  machine  has  been  devised  for  this  purpose  by  Mr.  Stron- 
hall,  of  Beeville,  Tex.  In  operation  this  apparatus  passes  over  one 
row  at  a  time  and  brushes  the  plants  from  both  directions  vigorously 
by  means  of  revolving  brushes  working  in  opposite  directions,  and 
the  stung  bolls  and  squares  which  fall  readily  are  caught  on  receiving 
trays  and  carried  to  bags  and  may  be  ultimately  burned  or  otherwise 
destroyed.  The  machine  may  be  adjusted  to  plants  of  different  ages 
within  certain  limits,  but  becomes  less  effective  as  the  plants  get 
larger.  As  witnessed  in  operation  the  present  season  by  Mr.  Town- 
send,  it  proved,  on  young  plants,  to  be  very  effective  and  satisfactory, 
collecting  a  large  percentage  of  the  weevils  and  the  stung  bolls  and 


squares.  The  temporary  advantage  of  the  use  of  this  machine  no 
doubt  will  be  considerable  and  may  materially  protect  the  early  cot- 
ton ;  it  probably  will  not  be  of  much  service  as  a  protection  for  late 
cotton  or  the  second  crop. 

L.  0.  Howard, 

Entomologist. 
Approved : 

James  Wilson, 

Secretary. 

Washington,  D.  C,  July  1,  1898. 


# 


UNIVERSITY  OF  FLORIDA 


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